Miniature airplane propeller and mounting therefor



N. E. WALKER Feb. 27, 1951 MINIATURE AIRPLANE PROPELLER AND MOUNTING THEREFOR Filed Aug. 28, 1948 INVENTOR. NeviZZe E. Walker Patented Feb. 27, 1951 OFFICE MINIATURE AIRPLANE PROPELLER AND MOUNTING THEREFOR Neville E. Walker, Portland, Oreg- Application August 28, 1948, Serial No. 46,702

My invention pertains to miniature airplanes, and relates particularly to a novel unitar propeller construction by means of which the latter is resiliently mounted for tipping out of its plane of rotation on said airplane.

The commercial production of such articles as miniature airplanes is a highly competitive industry, and there is an ever present quest for methods of increasing the efficiency of production and assembly. Decreasing the number of parts constituting the assembly is found advantageous, provided that constructional design is not complicated thereby. n the other hand, satisfactorily designed parts frequently entail complicated assembly procedures not always understood by the young minds of those for whom the toys are intended to please. The miniature airplane should be of simple construction, with but few parts which can be made in volume on automatic machines, and it is desirable that the parts should be packaged for sale while in fully or partially assembled condition. The propeller should be easily detachable for replacement, and should be flexibly mounted to prevent destruction by solid objects with which it may come in contact.

A principal object of my invention is to provide in a miniature airplane a unitary propeller rotatably and resiliently mounted thereon in such manner that the propeller may be easily twisted out of its operating plane to prevent breakage when the airplane strikes the ground nose first, and to permit the packaging of said airplane without first removing the propeller.

Another object is to provide in a miniature airplane a unitary propeller having a hollow enlarged central hub and a hollow cylindrical shaft extending axially therefrom by means of which said propeller is resiliently mounted on the nose of the airplane and held centrally therein to prevent accidental relative displacement.

A further object is to provide in a miniature airplane a unitary propeller having a hollow enlarged central hub and a hollow cylindrical shaft extending axially therefrom for detachably receiving one end of a twisted rubber band motor by means of which the propeller is resiliently held in its nose bearing on said airplane.

A still further object is to provide in a miniature airplane a unitary propeller detachably secured to a twisted band motor and resiliently mounted for rotation on said airplane, said mounted propeller being constructed and arranged to present decreased resistance to rotation imposed by said twisted band motor as the 4 Claims. (01. 4678) band motor is untwisted progressively from maximum distortion, said resistance retarding the effective speed of rotation of said propeller at greater distortions of the band motor, thereby providing for more uniform overall flying speed during a sustained flight of the airplane.

These and other objects and advantages of my invention will appear from the following detailed description taken in connection with the accompanying drawing, in which:

Fig. 1 is a perspective view of a miniature airplane fitted with a propeller embodying my invention;

Fig. 2 is a fragmentary side elevation, partly in section, showing details of construction of the propeller of my invention and the manner in which the same is mounted on the nose of an airplane; and

Fig. 3 is a fragmentary side elevation, partly in section, illustrating the manner in which the propeller may be tipped angularly out of its normal flying plane.

. The miniature airplane shown in the drawing for purposes of describing the function and construction of the propeller embodying my invention comprises a fuselage l which may be in the form of a rectangular wooden section. A single wing structure 2 extends through a transverse slot 3 formed in the fuselage. The tail assembly comprises a rudder 4 which extends vertically in a slot formed at the rearward end of the fuselage, and an elevator structure 5 secured horizontally across the under side of the fuselage by means of a rubber band 6 or other similar securing element.

' At the forward end of the fuselage is a nose piece formed of an integral piece of metal of U-shaped cross section. The principal web 1 of the nose piece overlies the tapered forward end of the fuselage, while the laterally projecting flanges 8 extend downwardly in engagement with the sides of said tapered forward end. Lips 9 project from the lower edges of the flanges 8 and are bent inwardly to engage the lower side of the forward end of the fuselage to hold the nose piece in place.

Extending rearwardly from the flanges 8 is a skirt In which defines laterally alined grooves for accommodating the bifurcated resilient landing gear support II. Said support preferably is made of a single piece of wire such, for example, as piano wire. At the middle of said wire an inverted U-shaped clip structure 12 is formed. The clip overlies the principal web 1 and engages the grooves formed in the flanges 8, whereby the clip is prevented from shifting laterally on the nose piece. The lower ends of the wire landing gear support are offset outwardly to provide axles upon which the wheels [3 are mounted.

The forward end of the nose piece is offset and broadened out to form a bearing M in which the propeller of my invention is resiliently mounted. A hole [5 is formed in said bearing to provide a bearing seat for maintaining the propeller in proper position with respect to the longitudinal dimension of the fuselage to achieve correct flying angle for the airplane. The twisted endless rubber band motor [6 is secured at its rearward end upon a hook I? depending from the fuselage, and at its forward end to the propeller presently to be described. The structure described hereinabove is fully described and claimed in U. S. Letters Patent No. 2,131,499 issued to me on September 27, 1948, and entitled Toy Aeroplane Propeller Mountings, of which the present invention is an improvement.

The propeller of the present invention comprises an integral body definin a pair of blades 43 extending from a central enlarged hub I9. An annular propeller shaft 26 is also formed integral with said propeller body and projects axially from one end of the hub. A bore 2| extends longitudinally of and axially through said hub and shaft for the purpose of receiving the free end of the rubber band motor IS. A slotted recess 22 is provided in the outer exposed surface of the hub diametrically across said bore to receive a pin 23 by which the rubber band is secured to the propeller.

The propeller shaft '20 is adapted to be received for rotation in the hole [5 formed in the bearing element of the nose piece. Since the nose piece is preferably made of metal, it is desirable that the part of the propeller which slidably engages the surface of the bearing head I4 also be of metal. For this purpose, and if the propeller is not constructed of metal, I provide a metal thrust washer 24 which is press fitted about the propeller shaft adjacent th hub 59. The propeller may be constructed of metal or wood, although I prefer to mold it of plastic material. In this manner, the blades, hub, shaft, bore and pin slot are formed simultaneously, thereby affording rapid, efficient and economical production.

The rubber band motor 15 extends forwardly from the hook I! through the hole 55 in the head of the nose piece and is secured in the axial bore 21 of the propeller by means of an easily retractable pin 23. The tension exerted by the rubber band tends to maintain the propeller in operative position, that is with the propeller shaft received in the hole of the nose Piece head [4. When the rubber band is in relaxed, or unwound, condition, the propeller may be swung out of its normal position to permit easy packaging of the toy airplane, thus obviating the necessity of removing the propeller. Similarly, such construc-- tion also permits the propeller to be moved angularly to prevent breakage thereof, as might occur when the airplane strikes a solid object at the end of its flight, or lands nose down on the ground. Upon removal of the airplane from such obstruction, the tension of the rubber band motor draws the propeller shaft into the bearing hole formed in the nose piece head and the airplane is ready for flight once again.

One of the difliculties in using a rubber band motor is that its distortion when twisted tends to provide greater torque when it is twisted to its maximum degree and a decreasing torque as said rubber band becomes untwisted. This tends to cause the propeller to be rotated at a higher speed at the commencement of flight and a correspondingly lower speed as the untwisting continues. By securing the propeller directly to the rubber band so that it tends to become seated more tightly as the over all length of the rubber band diminishes when twisted, a corresponding increase in resistance to rotation is secured. Thus, when the rubber band is twisted to its maximum degree it imposes a correspondingly increased friction to prevent rotation of said propeller. As said band becomes untwisted said friction decreases somewhat in proportion to the forc exerted by the partly untwisted rubber band. This construction causes the speed of the propeller under the influence of said rubber band to become more uniform over a sustained flight and increases the flying ability of said airplane.

I claim:

1. A propeller for a miniature airplane, said propeller comprising a body defining blades, an enlarged central hub having a bore therein and an annular bearing for maintaining axial rotation of said hub, said hub and annular bearing accommodating one end of a resilient band motor therein, and means spanning said bore releasably engaging the end of the resilient band motor lying within said bore.

2. A propeller for a miniature airplane, said propeller comprising a body defining blades, an enlarged central hub having a bore therein and an annular bearing for maintaining axial rotation of said hub, said hub and annular bearing accommodating one end of a resilient band motor therein, and a pin and socket structure spanning said bore releasably engaging the end of the resilient band motor lying within said bore.

3. A propeller for a miniature airplane, said propeller comprising an integral body defining blades, an enlarged central hub having a bore therein and an annular bearing for maintaining axial rotation of said hub, said hub and annular bearing accommodating one end of a resilient band motor therein, and a pin and socket structure spanning said bore releasably engaging the end of the resilient band motor lying within said bore.

4. A propeller for a miniature airplane, said propeller comprising an integral molded body defining blades, an enlarged central hub having a bore therein and an annular bearing for maintaining axial rotation of said hub, said hub and annular bearing accommodating one end of a resilient band motor therein, and a pin and socket structure spanning said bore releasably engaging the end of the resilient band motor lying within said bore.

NEVILLE E. WALKER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,258,963 Troje Mar. 12, 1918 1,767,769 Mee June 24, 1930 1,799,936 Timson Apr. 7, 1931 2,131.490 Walker Sept. 27, 1938 2,182,591 Kramer Dec. 5, 1939 

